Three initiation factors (IF-1, IF-2 and IF-3) are required for initiation of bacterial translation. What are their roles?
What will be an ideal response?
Ans: These factors are only associated with the 30S subunit and are released when the large ribosomal subunit (50S) joins the small subunit. IF-3 binds to free 30S subunits preventing them from associating with the 50S subunit; it enables them to bind to the mRNA at initation sites, and it checks the accuracy of binding the first aminoacyl tRNA. IF-2 binds a special initiator tRNA and brings it to the half P site (only the 30S subunit is bound to the mRNA). The GTPase activity of IF-2 is stimulated by the joining of the 50S subunit and may convert the 70S to an active form. IF-1 binds to the 30S subunit and prevents aminoacyl tRNA from entering the A site during initiation.
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Consider the following figure (Figure 24.5): From the data you can infer that:
A. Braincase volume is correlated with body size in the Homo lineage, but not in the extant great apes lineage. B. Species in the Homo lineage have larger body size than species in the extant great apes lineage. C. The extant great ape lineage shows the greatest amount of range in body size D. The Homo lineage shows the greatest amount of change in body size. E. Extant great apes are smarter than Australopithecines.
In sickle cell anemia, a ____ mutation in the ?-globin gene eliminates a ____
a. single base-pair; restriction site b. frameshift; restriction site c. nonsense; promoter region d. single base-pair; promoter region e. nonsense; restriction site
Bacterial genes have introns, and eukaryotic genes lack introns
Indicate whether the statement is true or false
Type A influenza virus genome is segmented; single stranded;RNA
a. true b. false